US756173A - Preserved wood and process of preparing same. - Google Patents

Description

PATENTED MAR. 29,. 1904.

I. P. LIHME. PRESERVED WOOD AND PROCESS OF PREPARING SAME.

APPLICATION FILED JUNE 7. 1902.

N0 MODEL.

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No. 756,173. r Patented March 29, 1904.

UNITED STATES PATENT OFFICE.

QIENS P. LIHME, 'OF CLEVELAND, OHIO, ASSIGNO R TO THE GRASSELLI CHEMICAL COMPANY, OF CLEVELAND, OHIO, A CORPORATION. OF

OHIO.

PRESERVED WOOD AND PRocEss OF PREPARING. SAME.

SPECIFICATION forming part of Letters Patent No. 756,173, dated Marci 1 29, 1904.

Application filed June 7,1902. Serial No. 110,623. (No specimens.)

T all h it y COW/067"": first-named salt, constituting an excellent pre- Be it known that I, TENS P. LIHME, a citizen servative, while the exterior portion of said of the United States of America, and a resident wood contains in its pores a superficial crust 0 of Cleveland, in the county of Cuyahoga and of varying depth, composed of silicate of zinc,

5 State of Ohio, have invented certain new and which is both insoluble and fireproof and useful Improvements in PreservedWood and closes in the soluble chlorid contained in the Processes of Preparing Same, (Case No. 3,) of interior of the wood. which the following is a specification. My inventionmay be more readily explained My invention relates to improvements in by referring to the accompanying drawings, I0 preserved woodand process of preparingsame, wherein and has for its object the production of wood Figure 1 illustrates in somewhat diagramadapted to withstand moisture, heat, the at- 'matic-manner apparatus adapted for practictacks of insects, and, in short, to render the ing my invention, and Fig. 2 shows in crosstreated wood as nearly impervious and unafsection a log or railroad-tie and a board after 5 fected by the elements as possible. their treatment in accordance with my im- Zinc chlorid has long been recognized as an proved process. extremely efficient if not the best wood pre- In practicing my process a hermeticallyservative known; but this has been coupled closed chamber is required, preferably of such 5 with the distinct disadvantage of the chemcapacity that a large charge of wood may be icals being quite readily dissolved from the readily inserted for treatment and easily re-- pores of the impregnated wood when exposed moved therefrom. I to the-action of the airand rain, thus leaving In the drawings I have indicated a large the wood entirely unprotected. It hasaccordchamber a, capable of being securely sealed 7 ingly ranked heretofore as a temporary preby a door 6 after the car a, carrying the wood 5 servative. The silicates, notably that of 'so-. 0? to be treated, has been pushed within the dium, have likewise been resorted tofor the chamber. Beneath the rails are shown steampurpose of fireproofing wood and have been coils e for inducing a high temperature withproven extremely efficient; but are open to the inthe treating-chamber. A vacuum-pumpf, same objection just mentioned. My present with its gage f, and a fluid-pump g, with its 3 invention accordingly proceeds with the idea corresponding pressure-gage g, are connected of combining the advantages of each of these with the said chamber a. Apr'essure-equalizer two extremely eflicient wood preserving It also is associated with the said chamber, the agents, while attaining practical permanence same having a movable weighted head it, in the preservative eifect secured. adapted to be raised in its cylinder upon the 3S Adverting briefly to my improved process increase in the pressure within the chamber and product, I may state, as introductory to beyond a given point. Upon introducing the a more extended description thereof, that the wood within the chamber it is first subjected process preferably consists in first effecting to a dry heat of about 200 by admitting steam 5 approximately the complete filling of the .to the coils e, which heating is continued un- 4 pores or saturation of the treated wood with til the wood has become thoroughly dried. a solution of zinc chlorid and thereafter sub- The vacuum-pump f is then put in operation jecting the same to the action of a silicate sountil the gage f remains substantially conlution, as sodium silicate, the useof vacuum stant. The valves c" 70 in pipes 71 k are then 9 and pressure being resorted to in order to obopened, the latter pipe connecting with the 45 tain the desired impregnation. Under this tank containingazinc-chlorid solution,where+ treatment it will be found that the body of the upon the treating-chamber is flooded with the wood is thoroughly impregnated with the said solution of zinc chlorid. Valve 11 is then closed and pump g is set in operation and a pressure of approximately two hundred pounds to the square inch is secured, which pressure is maintained ordinarily for five or six hours. -It may be well here to observe that the details of the treating process or operation vary considerably, depending upon the kind and condition of the wood under treatment, so that only general statements can be made which are applicable to average circumstances. This high pressure is continued until the wood has become thoroughly impregnated with the Zinc chlorid, this operation being greatly facilitated by the previous exhaustion of the air, after which the solution is pumped out of the chamber and into the containing-tank. (Not shown in the drawings.) Valve Z1 is thereupon closed and valve Z is opened to permit the solution of sodium silicate to be pumped through pipeZ into the treating-chamber. As before, the solution is maintained under a high pressure until the desired impregnation with silicate takes place. Treatment under two hundred pounds pressure for five or six hours will commonly suffice. By reason of the previous impregnation, however, it will be found that the formation of zinc silicate in the exterior portions of the wood through the combination of the two salts will clog or check the reaction more and more and cause the formation of an impervious layer or superficial crust within the pores of the wood. Depending again upon the kind of wood and conditions of treatment, this layer will be of greater or less thicknesssay, from one-eighth to three-quarters of an inch-but will be found sufficient to permeate the wood to form an effective exterior protection therefor. After withdrawing the silicate solution from the chamber steam may be admitted to the coils toeifect the rapid drying of the treated wood or the car may be removed from the chamber, permitting its recharging while the treated wood is allowed to dry naturally before making use of it.

It is scarcely necessary to state that proper precautions should be taken to insure the free access of the separate solutions to all of the wood under treatment. The strengths of the solutions used ordinarily will be from five per cent. to ten per cent., no precise general directions being practicable, however, since in this matter the process depends as well upon the kind and condition of the wood treated.

This process is particularly valuable in preserving railroad-ties, and in Fig. 2 is shown in cross-section a tie after being subjected to my above-described process, as well as a similar view of a board likewise treated. Each will be found to have a central portion in thoroughly impregnated with the preservative zinc chlorid and an external Zone or permeating-crust y of insoluble zinc silicate. This latterviz., the protective crust of zinc silicate is of course perfectly insoluble, impervious to water, and relatively unaffected by fire or extremes of heat and cold and the attacks of insects. Hence it forms an ideal protection for the body of wood inclosed thereby.

Having now described my invention, I make claim to the following:

1. Theherein-described process for treating wood, consisting in effecting its thorough impregnation with zinc chlorid and thereafter subjecting the wood to the action of a soluble silicate, preferably sodium silicate, whereby a layer or superficial crust of zinc silicate is formed in the exterior portions of the wood, substantially as set forth.

2. The process substantially as herein described, for preserving railroad-ties and the like, which consists in effecting the thorough impregnation of the wood with a Zinc-chlorid solution by means both of vacuum and high pressure, and then subjecting said wood to a solution of a soluble silicate, preferably sodium silicate, under pressure whereby zinc silicate is precipitated-in the pores of'the wood to a moderate depth.

3. The product of the herein described process, comprising wood, such as railroadtics, thoroughly impregnated substantially throughout its interior with zinc chlorid, and its exterior portions permeated with a protective layer of Zinc silicate, substantially as set forth.

Signed by me at Cleveland, Ohio, in the presence of two subscribing witnesses, this 26th day of May, A. D. 1902.

IENS P. LIHME.

Witnesses:

GEORGE B. RILEY, ALBERT LYNN LAWRENCE.

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